The wife of "Hour of Power" televangelist Robert H. Schuller, Arvella Schuller, died Tuesday at the University of California, Irvine Medical Center after a brief illness, her family announced. She was 84.

Arvella Schuller helped her husband's ministry as it started at a Southern California drive-in theater in 1955 into a megachurch with worldwide television audience of 20 million viewers, reported The Associated Press.

"My heart is deeply saddened to inform you of the passing of my grandmother, Arvella Schuller," current "Hour of Power" pastor Bobby Schuller wrote on the church's website. "She went to be with our Heavenly Father this morning, dying peacefully of natural causes. She was the power behind the Hour of Power. Her music, vision, and care for the message has touched countless hearts."

Arvella Schuller was the church organist at her husband's ministry and served as executive producer and program director for the "Hour of Power" television program, which began in 1970. The AP said she went on to develop a private school that was connected with the church.

"This ministry is committed to carrying on the incredible movement she helped start with my grandfather many years ago, to reach millions of hurting people with the positive message of God's love," Bobby Schuller added in his statement. "She will be missed."

The church moved into the iconic Crystal Cathedral in 1980, a 10,000-glass-paned structure that was showcased during it televised services, according to the Los Angeles Times. Arvella Schuller is also remembered for starting a 24-hour crisis line for the church.

"She was a natural leader, a strong leader. When there was a decision to be made, she made it without hesitation," Marc Riley, who started working with the Schuller's ministry in 1994 as a musical assistant, told the Times.

The church, now known as the Shepherd's Grove, sold its Crystal Cathedral campus to the Roman Catholic Diocese of Orange in 2011 after falling on hard financial times, according to the Times.

The AP reported that both Schullers became ill earlier this month, but the elder Schuller was recently released to a rehabilitation facility. The family told the AP that a private memorial service is being planned.

The wife of "Hour of Power" televangelist Robert H. Schuller, Arvella Schuller, died Tuesday at the University of California, Irvine Medical Center after a brief illness, her family announced. She was 84.